Mobile Miniature Research Articles

Development of mobile miniature natural gas liquefiers

With increasing consumption of natural gas (NG), small NG reservoirs, such as coalbed methane and oil field associated gas, have recently drawn significant attention. Owing to their special characteristics (e.g., scattered distribution and small output), small-scale NG liquefiers are highly required. Similarly, the mixed refrigerant cycle (MRC) is suitable for small-scale liquefaction systems due to its moderate complexity and power consumption. In consideration of the above, this paper reviews the development of mobile miniature NG liquefiers in Technical Institute of Physics and Chemistry (TIPC), China. To effectively liquefy the scattered NG and overcome the drawbacks of existing technologies, three main improvements, i.e., low-pressure MRC process driven by oil-lubricated screw compressor, compact cold box with the new designed heat exchangers, and standardized equipment manufacturing and integrated process technology have been made. The development pattern of “rapid cluster application and flexible liquefaction center” has been eventually proposed. The small-scale NG liquefier developed by TIPC has reached a minimum liquefaction power consumption of about 0.35 kW·h/Nm3. It is suitable to exploit small remote gas reserves which can also be used in boil-off gas reliquefaction and distributed peak-shaving of pipe networks.

СПЕЦИАЛЬНАЯ СТРАТЕГИЯ ОБРАБОТКИ СЛОЖНОПРОФИЛЬНЫХ КОНИЧЕСКИХ ВИНТОВЫХ ПОВЕРХНОСТЕЙ РАБОЧИХ ОРГАНОВ ОДНОВИНТОВЫХ КОМПРЕССОРОВ

The article deals with the problems arising during the shaping of complex profile tapered helical surfaces. These surfaces form the geometry of the working bodies of single-screw miniature compressors, which have great prospects for use in mobile miniature compressor plants, which is especially important for medical and space technology, robotics, oil and gas and mining industries. Due to the fact that the capabilities of existing CAD systems do not allow obtaining three-dimensional models of these surfaces, the problem of preparing a control program for a CNC machine arises, since the calculation of the tool path in CAM systems when processing complex surfaces is impossible without a three-dimensional surface model. To solve the problem, an automated programming system was developed that implements a formalized toolpath calculation in accordance with the proposed special processing strategy for conical helical surfaces. As the initial data for calculating the toolpath, the system needs information about the tool geometry and the helical surface in a parametric form, which makes it possible to abandon the construction of a three-dimensional surface model. The results of processing prototypes for the proposed strategy are given.

Mobile miniature X-ray evaluation and pneumoconiosis: the role of the Clinica del Lavoro in Milan (1941-1948)

«Mobile miniature X-ray evaluation and pneumoconiosis: the role of the Clinica del Lavoro in Milan (1941-1948)». Since the end of the 19th century, X-rays have been used to detect lung diseases. In Italy, 207,096 miniature chest radiographs were taken from 1941 to 1948. Traditional radiographs gave better results, but miniature chest radiographs were useful for screening. Indeed, the development of mobile miniature chest radiography units resulted in an improvement in mass X-rays screening for the detection of penumoconiosis. These mobile miniature units were mounted on a bus chassis, a solution that allowed to easily reach workers. The authors analyze some models of X-ray wagon units used by the “Clinica del Lavoro” in Milan in the 1950s. From the point of view of medical museology, the preservation of these devices requires appropriate spaces.

Design and application of a mobile miniature current probe for analysing the cause of EMI noise in IC circuits

This study is based on International Electrotechnical Commission (IEC) 61967-4 standards for measuring electromagnetic emissions and interferences at the chip level. Conventional measurement methods using fixed SMA connectors were replaced with an improved radio frequency current probe featuring semi-rigid coaxial cables, making it capable of taking mobile measurements, enhancing the flexibility and convenient probing usage. To effectively assess the practical value of the improved probe, the authors have referred to the standard designs provided in IEC 61967-1 to manufacture a four-layer digital circuit board that controls the screen of an on-board navigational screen for automobiles. Circuit board electromagnetic interference (EMI) noise frequency and level readings from the improved probe were also compared with three other measurement methods, namely magnetic field probes available in the market, TEM cells, and the 10-m far-field measurement method. The results demonstrated the capability of the improved probe to effectively identify sources of noise at the chip-level during the IC design phases, helping with root cause analysis and allowing EMI noises experienced by the product to be solved promptly during the process of electromagnetic compatibility design optimisation and analysis.

Mobile Mini-mechanism for Moving in Pipe with Small Diameter

The paper deals with a mobile miniature mechanism which was moved inside glass pipe. The mobile miniature mechanism consists of driving and driven body, which is moved by magnetic force. In the theoretical analysis of miniature mechanism movement its mean velocity on the base of two elastic masses impact model is examined. In experimental part dependencies of attractive force and repulsive force on distance are examined.

A MEMS-Based Inertial Navigation System for Mobile Miniature Robots

A real-time inertial navigation system (INS) for mobile miniature robots was proposed, which mainly consists of hardware platform and software system. Based on the principles of embedded system, and by use of MEMS-based inertial measurement units (IMU) and micro control units (MCU) including ARM and CPLD, a compact, low-power-consumption, low-cost, and universal real-time hardware platform was constructed for the navigation system. Besides, a μC/OS-II real-time operating system was transplanted for software developing, where all the algorithms of digital signal processing, data interpolation, navigation calculating were realized. Furthermore, a fuzzy system was designed for sensor data fusion so as to achieve accurate navigation. Finally, the MEMS-based INS was fully tested via experiments on a mobile miniature robot. Experiments results show that average error of the heading angle estimation is about 0.56%, average error of Attitude angle estimation is 2.57%, and the maximum error of plane position is about 10%, which indicates that this INS satisfies requirements of mobile miniature robots.

A visually guided collision warning system with a neuromorphic architecture

We have designed a visually guided collision warning system with a neuromorphic architecture, employing an algorithm inspired by the visual nervous system of locusts. The system was implemented with mixed analog-digital integrated circuits consisting of an analog resistive network and field-programmable gate array (FPGA) circuits. The resistive network processes the interaction between the laterally spreading excitatory and inhibitory signals instantaneously, which is essential for real-time computation of collision avoidance with a low power consumption and a compact hardware. The system responded selectively to approaching objects of simulated movie images at close range. The system was, however, confronted with serious noise problems due to the vibratory ego-motion, when it was installed in a mobile miniature car. To overcome this problem, we developed the algorithm, which is also installable in FPGA circuits, in order for the system to respond robustly during the ego-motion.

Intraoperative radiotherapy (IORT) as a boost in patients with early breast cance

695 Background: External beam radiotherapy (EBRT) after breast-conserving surgery (BCS) with 45–50 Gy is the gold-standard in patients with limited stages of breast cancer. Most recurrences appear close to the tumorbed. Therefore this area is often provided by a boost in routine practice but no standard technique exists. The boost is applicated either by EBRT-techniques, by brachytherapy or by intraoperative radiotherapy (IORT). Since february 2002 IORT is delivered in breast cancer patients by a mobile miniature x-ray source (Intrabeam™). Methods: From 2/2002 -10/2003 70 patients with breast carcinomas were treated by IORT after BCS. 45 patients received IORT as a tumorbed-boost, followed by EBRT. Median age was 63 years (43.1–86.5). Median tumor size was 14 mm (6–45). Pathology results showed ductal-invasive histology in 18, lobular-invasive in 13, mixed in 10, tubular-invasive in 2 patients and medullar and mucinous histology in 1 patient respectively. Treatment time took 20 minutes (18.6–48.8). In mos...

Intraoperative radiotherapy (IORT) as a boost in patients with early breast cance

695 Background: External beam radiotherapy (EBRT) after breast-conserving surgery (BCS) with 45–50 Gy is the gold-standard in patients with limited stages of breast cancer. Most recurrences appear close to the tumorbed. Therefore this area is often provided by a boost in routine practice but no standard technique exists. The boost is applicated either by EBRT-techniques, by brachytherapy or by intraoperative radiotherapy (IORT). Since february 2002 IORT is delivered in breast cancer patients by a mobile miniature x-ray source (Intrabeam™). Methods: From 2/2002 -10/2003 70 patients with breast carcinomas were treated by IORT after BCS. 45 patients received IORT as a tumorbed-boost, followed by EBRT. Median age was 63 years (43.1–86.5). Median tumor size was 14 mm (6–45). Pathology results showed ductal-invasive histology in 18, lobular-invasive in 13, mixed in 10, tubular-invasive in 2 patients and medullar and mucinous histology in 1 patient respectively. Treatment time took 20 minutes (18.6–48.8). In most cases a spherical applicator with a 4.5 cm diameter was chosen (3.0–5.0). A single high-dose (20 Gy) can be applicated on the applicators surface, reaching the wrapped breast tissue up to a tissue depth of 1.5 cm. After wound-healing all IORT-patients were treated by EBRT with 46 Gy. Results: After treatment no skin necrosis were observed. 3 patients had woundhealing problems, 2 an erythema °II on their first day after surgery. After a maximum follow-up of 22 months, patients showed good cosmetic results.1 patient had to have secondary mastectomy because of a previously not known mulitfocality, a second patient developed cervical lymph node metastases 2 months after BCS. In both casese EBRT was omitted. Another patient presented 10 months after EBRT with a multifocal relapse in her previously treated breast with skin metastases. She died 4 months after the secondary mastectomy. Conclusions: IORT with the Intrabeam system is a comfortable method to deliver a single boost to the tumorbed. After BCS, the tissue can be ideally adapted to the applicators surface and be treated by low-distance x-rays. By IORT the miss of the target, as it often appears in EBRT of the breast, can be avoided. No significant financial relationships to disclose.

RoboPoint—an autoclavable interactive miniature robot for surgery and interventional radiology

The main drawback of current robot assisted methods is the additional expenditure for planning as well as technical preparation. The goal of this project was the realisation of an autoclavable mobile miniature robot which can be integrated easily into the standard OR, and minimises the additional technical preparation. The new miniature robot consists of an autoclavable-positioning unit with two or four active and two passive axes (position at z-axis and rotation around z-axis). The unit is positioned versus the patient under navigation control and is fixed rigidly by a mechanical arm. The system integrates the robot's workspace and the planning model within an optical and electromechanical controlled execution mode. The system reaches an absolute accuracy of about 0.3 mm reproducibility equal to competitive navigation and robot assisted systems. Forces of up to 20 N can be generated by the positioning unit. The system is fully compatible to the standard OR and its accuracy as well as its stability is high. Due to its transparent system structure and modular concept, the miniature robot can be used within a wide range of medical applications, such as the insertion of extraoral implants and the milling of bone.

Neural reinforcement learning for behaviour synthesis

We present the results of a research aimed at improving the Q-learning method through the use of artificial neural networks. Neural implementations are interesting due to their generalisation ability. Two implementations are proposed: one with a competitive multilayer perceptron and the other with a self-organising map. Results obtained on a task of learning an obstacle avoidance behaviour for the mobile miniature robot Khepera show that this last implementation is very effective, learning more than 40 times faster than the basic Q-learning implementation. These neural implementations are also compared with several Q-learning enhancements, like the Q-learning with Hamming distance, Q-learning with statistical clustering and Dyna-Q.